1. Field of the Invention
The present invention relates to packing containers and more particularly to packing containers provided with opening arrangements.
2. Description of the Prior Art
Conventional, so-called non-returnable, packages for liquid foodstuffs are manufactured at present in most cases with the help of modern packing machines of the type which both form, fill and close finished packages from either a web or from prefabricated blanks of a laminated packing material, generally plastic-coated paper. Packages are manufactured, for example, from a web wherein two longitudinal edges of the web are combined with one another in an overlap joint so as to form a tube which thereafter is filled with the intended contents and is divided into filled, cushionlike packing units by repeated transverse sealing of the advancing tube below the contents level of the tube. The sealed packing units are separated from one another by cuts in the transverse seals and are given the desired final geometric shape, usually parallelepipedic, by means of a subsequent shaping and sealing operation during which the triangular, double-walled corner lugs of the separated packing units are folded in against, and sealed to, the outside of the packages.
For the convenience of the user the packages are provided in most cases with some type of opening arrangement with the help of which the packages easily can be broken into without the use of scissors or similar tools. A further demand made on an opening arrangement functioning well is that it should provide the package with good pouring properties which means, among other things, that it should be possible to pour out the contents of the package conveniently in a coherent and well-directed jet.
Conventional packages provided with an opening arrangement of the type described as a rule meet the consumer demands raised in respect of openability and good pouring properties but, as far as is known, none of these opening arrangements up to now has provided a satisfactory solution to the further consumer requirement, that the package should also be functionally reclosable so as to give, after only a partial emptying of the contents, at least physical protection to the remaining contents until the next occasion for emptying.
Among a number of earlier, one was based on providing at least one, preferably the bottom one, of two strip portions with a thin layer of pressure-sensitive adhesive, with the help of which the two strip portions could be recombined with good adhesion after each opening. Another suggestion was to provide the opening arrangement with a mechanical reclosing arrangement of the type, for example, which is described in Swedish patent no. 451 012, and according to which the upper strip portion possesses a gripping strip applied separately to its underside which, on reclosure of the container, is adapted to hook mechanically onto the free end of the bottom strip portion serving as a pouring edge.
The problem with an opening arrangement in accordance with the first-mentioned suggestion is that the adhesive layer, which is freely exposed after the opening of the container, is sensitive to dust and similar dirt occurring in the surroundings of the container which easily fastens onto, and "neutralizes" the adhesiveness of this layer necessary for the reclosing. The contents of the package too, which during the pouring come into contact with the underlying, preferably adhesive-coated, strip portion tend to adhere to, and wet, the sticky surface of the adhesive layer, which contributes further to the impairing of the reclosing capacity of the opening arrangement. The problem with the mechanical arrangement described above is that it has been found to be much too difficult in practice, on reclosing of the container, to apply the upper strip portion provided with the gripping strip in the required correct position in relation to the pouring edge of the bottom strip portion in order to retain effectively the upper strip portion by an engagement between the gripping strip and the pouring edge.